Art of converting phosphorites.



UNITED STATES PATENT OFFICE. v

HENRY V. DUNHAM, 0F BAINBBIDGE, TOE-K; ABSIGNOR. TO NACIBEMA CHEMICAL COMPANY, A COMORATION 01.3" VERMONT.

ART .1' CONVERTING; 2HOSBHOBITES 1,034,090. No Drawinfia' To all whom it may concern:

Be it known that I, HENRY V. DUNHAM, a citizen of the United States, residing-at Bainbridge,.in the county of Chenango and State of New York, have invented or discovered certain new and useful Improve-- ments in the Art of Converting Phosphor ites, of which the following is a specification.

This invention or discovery relates to the treatment of phosphorites or phosphate rock to render the same suitable for fertilizing purposes, and has for its object to. so treat the phosphate rock, by arelatively inexpensive process, that the treated product will contain a relatively large percentage of citrate soluble or Water soluble phosphate which is suitable for plant life, and which is known in the art as available phosphate. I

It is well known that phosphate exists in natural phosphorites or phosphate rock in a form not immediately available for plantlife, and that such Iock must first be made available, either by the action of" the soil on the rock or by some chemical process of 1 treating the rock, before it is suitable'for agricultural purposes.

Many attempts have been made to secure a large percentage of available phosphate bymethods other than the usual method which requires therock to be treated with about its equal weight of sulfuric acid. Some of these attempts have comprised calcining methods, the more usual method consisting in adding to the finely ground .rock certain chemicals and suitable fluxes and then heating the mixture to varying degrees in a blast furnace or indirectly through heating ovens. In most of these attempts to secure a high available content of citrate soluble or water soluble phosphate from the insoluble phos phorites, salts of soda or potash, or a mixture of the two, have been employed, although in some cases varying amountsof calcium salts have been added. So far as I am aware these processes have never come into practical commercial use, and doubtless Specmcaflon of Letters Intent, a umnon filed m 7, 191-1. Serial 11v. $873,281.

Patented Jul 30., 1912..

tion of these salts acts as an adulterant, to agreater or less extent.

This invention or discovery consists in a method of treating natural phosphorites by meansof-acid, and then subsequentlycah chain}; the same, and by this method, when properly carried out, I convert a Very large amount of the insoluble phosphorite into what is generally termed by, the trade as citrate-soluble and which. is immediately available for plant'l-ife. I

In carrying this invention or discovery into. effect the phosphate rock is first ground ground cient water to form a thin mud when the acid andwater have been well mixed with the ground rock or phosphorite' As varying qualities of rock require varying percentages of acid, the invention is not to be understood as being limited to the use of 15% of 'the acid or to the use of 50 B. sulfuric acid. This acid is, however, mentioned because it is the usual commercial quality known as chamber acid used in the fertilizer industry. j

An example of a mixture which 'has proved to be successful is as follows: 100 lbs. finely ground phosphate rock. 15 lbs. of 50 sulfuric acid, 30 lbs. of water. Theacid is preferably added to the water and then this mixture to the pulverized rock. When the acid and water are added to the ground rock and thoroughly mixed therewith more or less heat is generated and the acid acts more or less upon the rock, which is not detrimental. When a thorough mixture of the above substances has been obtained the material is ready for calcining. The percentage of water stated is referably employed in order to secure a tliorough mixture of the small percentage of acid stated with the ground rock. Of course if more acid be used less water will be required. .Also either the'water or the acid mlght be firstmixed with the ground rock and the other liquid might then be added. The mixture above mentioned, of rock, acid and water, is then heated inany suitable calcining furnace to a fairly high heat, depending somewhat upon the grade of rock used, but to a point from a dull red to awhiteheat, and this heating treatment is continued for about one hour, the length of time of the heatmg treatment ,depending somewhat upon the quality or grade ofrock being treated. Af-. ter the rockhas been properly calcined it is removed from the furnace, and when it has cooled it is ground to a'. fine powder or from 80 to .100 mesh. It is then readyto be applied to'the soil or mixed with other ingredients which are generally used in the manufacture of fertilizers. The phosphate in the rock treated as above described exists mainly in the form of a citrate soluble prodnot, and is thus available for plant life. Just what-chemical reaction takes place in. the above described process has not been determined, but the result stated is probably largely due to the action of the nascent gases formed by the calcining process, as a large portion of the S0 added in the form of sulfuric acid is expelled from the mixture by the calcining process.

By the foregoing process phosphorites may be'converted into suitable condition for use as fertilizers at very much less expense than is involved in the usual process of conversion, owing to the fact that in this new process only a relatively small amount of sulfuric acid is required.

Having thus described my invention or discovery I claim and desire to secure by Letters Patent:

The herein described process for converting phosphorites, consisting in mixing with the ground rock about 15% of its weight of sulfuric acid and about 30% of its weight of water, and then calcining the rock by subjecting the same to a high heat for about an hour.

In testimony whereof I afiix my signature, in presence of two witnesses.

HENRY V. DUNHAM.

Witnesses:

A. A. DUNHAM, O. L; ORUMB. 

